A challenge to the effective presentation of multimedia content is time synchronization, for example the synchronization of the visual content of a motion picture or video to the corresponding sound. Depending on the exact media involved, the lack of time synchronization can be caused by a variety of problems. For example, a film loop in a movie theater or on a television broadcast may have its sound noticeably out of synchronization with its picture because of operator difficulties in establishing the appropriate tension on the film. Another potential cause of synchronization errors is a difference in the transmission time between the video, which is often sent via satellite, and the audio, which is often sent over land lines which provide greater security and reliability; which procedure generates an undesirable time differential between picture and audio. Synchronization problems also commonly occur in live broadcasts when digital effects are inserted into video, causing a time delay in the visual stream but not in the audio stream.
Prior art synchronization techniques include the use of clapsticks in original double-system filming (i.e., the common practice of recording sound separately from the filmed image stream) to provide a visible and audible cue point to align picture and sound; continuous time code (i.e., a standardized clock reference) recorded with sound and visually recorded on film for time alignment of picture and sound; and, continuous time code integrated into video picture and sound, used to provide time references for synchronization of picture and sound when they are processed separately, as is commonly the case. Generally, however, prior art synchronization techniques rely on a human to detect a lack of synchronicity and to attempt to re-align the content.
It is therefore an objective of the present invention to provide an improved system and method for synchronizing audio to motion picture or video.
Yet another objective of the present invention is to economically utilize speech recognition techniques for synchronizing audio to visual content.